1. Field of the Invention:
The present invention relates to a cooling structure for cooling an engine with a cooling medium or coolant such as water, a lubricant, or the like.
2. Description of the Relevant Art:
Japanese Laid-Open Utility Model Publication No. 58-37920 discloses an engine cooling structure for cooling an engine by supplying a liquid coolant such as water, an engine lubricant, or the like to suitable locations in the engine with a pump. The disclosed engine cooling structure has a coolant passage defined in a water jacket around a cylinder for the cooling liquid to flow therethrough to cool the cylinder, the cooling liquid also serving as a sound insulation.
The disclosed engine cooling structure is advantageous over a cooling structure for cooling an engine with air in that it can cool the engine and reduce the noise of the engine more effectively than the air-cooled engine system.
Cooling structures for cooling engines with water are associated with radiators. As disclosed in Japanese Laid-Open Utility Model Publication No. 61-92713, a cooling structure for cooling an engine with a lubricant is combined with an oil cooler for cooling the lubricant. In either case, a radiator of some kind for lowering the temperature of the cooling medium is required in addition to the engine itself. Therefore, while the conventional liquid-based engine cooling structure can attenuate the engine noise, it is necessary to provide a space for installing the radiator in addition to the engine itself. As a result, the overall engine system is large in size. This problem has proven particularly undesirable with respect to general-purpose engines for use on various working machines since such engines are required to be compact.
In view of the aforesaid drawback of the conventional cooling structures for cooling engines with cooling liquids, the present invention has been made in an effort to effectively eliminate the problem.